A femtocell is a small base station that may be placed in a customer's residence or in a small business environment, for example. Femtocells may be utilized for off-loading macro radio network facilities, improving coverage locally in a cost-effective manner, and/or implementing home-zone services to increase revenue. Femtocells, like macro base stations, may be enabled to connect “standard” phones to a cellular provider's network by a physical broadband connection which may be a digital subscriber line (DSL) connection, fiber connection, and/or a cable connection, for example. Since the traffic between a customer's premises femtocell equipment and the operator's network may be traversing a public network, the traffic may be prone to various risks.
Communication between femtocells and one or more cellular provider's networks enables operation in private and public areas. The capacity of a femtocell may be adequate to address a typical family use model supporting two to four simultaneous voice calls and/or data, for example.
An important characteristic of femtocells is their ability to control access. In an open access scenario, any terminal and/or subscriber that may be subscribed to any cellular base station may be allowed to communicate with the femtocell. Accordingly, the femtocell usage may somewhat resemble that of a macrocellular system. In a closed access scenario, only a limited number of terminals and/or subscribers that may be subscribed to a given cellular base station may be allowed to communicate with the femtocell. In this regard, the cellular base station may be perceived as being deployed for private usage.
A regulatory issue with regard to femtocells is that they use licensed frequencies that radiate at a very low power in a controlled environment. It may be likely that they may not require a license from a local authority, as macrocellular base stations do. An additional regulatory issue may arise from the relationship between a femtocell operator and a broadband services operator. One possible scenario may include the broadband operator being unaware of the existence of a femtocell operator. Conversely, the broadband operator and femtocell operator may have an agreement or they may be the same operator, for example. Interference between femtocells may be an issue for femtocell deployments based on wideband technologies such as WCDMA, or OFDM, for example, because initial operator deployments may use the same frequency for both the femtocell and the macrocellular networks or due to the proximity of femtocell base stations in dense urban areas
There are a plurality of design models for deployment and integration of femtocells, for example, an IP based radio network controller (RNC) node B (Iu-b) interface, a session initiation protocol (SIP) based approach using an Iu/A interface, use of unlicensed spectrum in a technique known as unlicensed mobile access (UMA) and/or use of IP multimedia subsystem (IMS) voice call continuity (VCC), for example.
In an Iu-b model based femtocell deployment approach, femtocells may be fully integrated into the wireless carrier's network and may be treated like any other remote node in a network. The Iu-b protocol may have a plurality of responsibilities, such as the management of common channels, common resources, and radio links along with configuration management, including cell configuration management, measurement handling and control, time division duplex (TDD) synchronization, and/or error reporting, for example. In Iu-b configurations, mobile devices may access the network and its services via the Node B link, and femtocells may be treated as traditional base stations.
In a SIP based femtocell deployment approach, a SIP client, embedded in the femtocell may be enabled to utilize SIP to communicate with the SIP-enabled mobile switching center (MSC). The MSC may perform the operational translation between the IP SIP network and the traditional mobile network, for example.
In a UMA based femtocell deployment approach, a generic access network (GAN) may offer an alternative way to access GSM and GPRS core network services over broadband. To support this approach, a UMA Network Controller (UNC) and protocols that guarantee secure transport of signaling and user traffic over IP may be utilized. The UNC may be enabled to interface into a core network via existing 3GPP interfaces, for example, to support core network integration of femtocell based services by delivering a standards based, scalable IP interface for mobile core networks.
In an IMS VCC based femtocell deployment approach, VCC may provide for a network design that may extend an IMS network to include cellular coverage and address the handoff process. The IMS VCC may be designed to provide seamless call continuity between cellular networks and any network that supports VoIP, for example. The VCC may also provide for interoperability between GSM, UMTS, and CDMA cellular networks and any IP capable wireless access network, for example. The IMS VCC may also support the use of a single phone number or SIP identity and may offer a broad collection of functional advantages, for example, support for multiple markets and market segments, provisioning of enhanced IMS multimedia services, including greater service personalization and control, seamless handoff between circuit-switched and IMS networks, and/or access to services from any IP device.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.